1. Field of the Invention
The present invention relates to image data enhancement apparatus and methods, and more particularly to apparatus and methods of filtering data for enhancement of images and efficient data storage and transmission.
2. Description of the Prior Art
In the prior art there are image data compression systems available. The following are systems known to the inventors herein.
U.S. Pat. No. 4,006,298 generally discloses a system having an image gray scale using 64 discrete levels of brightness. However, the patent does not disclose a method for filtering gray scale transitions based upon comparison of predetermined bits of a current picture element with previous and subsequent picture elements.
U.S. Pat. No. 4,177,470 shows a system wherein a binary data signal is operated on to reduce the number of bits in the signal without reducing information content of the signal. The patent shows basically a data compression system. However, the patent does not disclose apparatus or method for filtering gray scale transitions in image data based upon comparison of current picture element information with previous and subsequent picture element information.
IBM Technical Disclosure Bulletin, Vol. 22, No. 7, December 1979, pages 2980-2985, J. L. Mitchell, "Vertical Reference Coding for Digital Gray-Level Images", discloses a data compression scheme for gray level images which recognizes and employs vertical redundancy. Three methods are disclosed for coding gray scale data relative to corresponding picture element positions on a previous scan line. All three methods rely on the value of the preceding pel in employing vertical redundancy to compress image data. The concept disclosed in the referenced article, differs from the present invention in that the article does not disclose a method for filtering gray scale transitions in image data based upon a comparison of predetermined bits of a current picture element with corresponding bits of a previous picture element and a subsequent picture element to detect a gray scale transition.
U.S. Pat. No. 4,210,936 shows a method and apparatus which achieves compression of image data by a reduction matrix which utilizes less gray scale data than is generated from the original picture element matrix. For example, if a picture element gray level requires four bits of data, then the reproduction of the gray scale requires only one bit of data. The patent differs from the present invention in that a gray scale function signal is required in addition to the picture element signal to adequately reproduce the original image and, there is no gray scale filtering shown in the patent as is disclosed and claimed with respect to the present invention.
U.S. Pat. No. 4,229,768 teaches an apparatus which compresses binary image signals by a selective run length compression technique. Although the patent does show the comparision of a sequence of picture elements in a scan line, there is no method or apparatus for filtering gray scale transitions based upon the results of such comparison.
U.S. Pat. No. 4,280,144 discloses apparatus and method for improving quality of a course scan, line print image processing system. An encoder assigns a code to a coarsely scanned picture element representative of the reflectance characteristic thereof. For fine reproduction of coarsely scanned data, the coarsely scanned picture element is summed with at least four adjacent horizontal and vertical picture elements to reproduce a fine picture element comprising at least four subelements. Although the patent obtains information for determining a fine value of a particular picture element from adjacent picture elements, the patent in effect teaches a method for expanding data from a coarse scan to a fine representation and does not in fact filter image data based upon detection of gray scale transitions as is disclosed and claimed by the present invention.
The prior art of which the inventors herein are aware does not show nor suggest the apparatus and method disclosed and claimed herein.